1. GENERATOR HEAT RECOVERY CONSIDERATIONS IN ARCTIC VILLAGE APPLICATIONS LCDR William Fraser, P.E.

2. Who We Are
Alaska Native Tribal Health Consortium Division of Environmental Health & Engineering
June 2011

3. ANTHC Non-profit, statewide organization
Provides a range of medical and community health services for more than 125,000 Alaska Natives.
Part of the Alaska Tribal Health System, which is owned and managed by the 229 federally recognized tribes in Alaska and by their respective regional health organizations.

6. ANTHC History 1970s-1990s: Regional health organizations in Alaska
Passage of P.L established ANTHC, the only THO established by statute
December 1997: ANTHC incorporated as non-profit 501(c)(3)
June 1998: Initial contract with IHS.

7. ANTHC History
October 1998: Contract expanded to include Environmental Health & Engineering
October 1998: ANTHC becomes a P.L Title III Self-Governance entity, signing the Alaska Tribal Health Compact

8. DEHE Designs and Constructs Health and Sanitation Facilities
Provides operations support
Monitors & develops standards for mitigating climate change impacts
Health impact studies
Environmental Grants & training

10. Water & Sewer- Why?

11. What does this have to do with Heat Recovery?
Hospitalizations are 5 times higher in communities w/o piped water & sewer.
Typical Fuel consumption for an Arctic WTP w/ piped water & sewer: ,000 Gal / Year Fuel Oil
Fuel Prices between $6.00 & $8.00 / Gal. and rising.
Heat recovery can help make it affordable.

12. Extreme Climate

13. High Energy Use

14. HEAT RECOVERY FROM POWER PLANTS
2 basic types:
Jacket recovery
Stack recovery
Small Scale: 50 KW to 3500 KW
Ideal for space heat and process heat
Considered a fuel saver, not a primary source of heat.

15. Kwigillingok Generator Facility

16. ADVANTAGES OF HEAT RECOVERY
Very green- reduces carbon footprint.
Can dramatically increase the economic viability of a community water system.
Adds additional redundancy to the building heating system.

17. DISADVANTAGES OF HEAT RECOVERY
Requires an agreement with the power utility, often with a charge for waste heat.
Usually increases the complexity of the heating system, especially in Washeterias.
Requires additional maintenance and coordination between power utility and building owner.

18. Other Solutions

19. SO YOU WANT TO BE GREEN What do you need to know before you start?
Estimating available waste heat
Deciding on a heat recovery strategy
Selecting system components

20. WHAT DO YOU NEED TO KNOW BEFORE YOU START?
Who owns the generators and what are their conditions?
Do you have a viable path between the waste heat source and the building?
What type of building are you serving?
Are there other buildings served by the waste heat?
What type of monitoring do you want?
Who is going to maintain it?

21. ESTIMATING AVAILABLE WASTE HEAT
QA =
QGEN – QPIPE - QO
QA: Minimum available waste heat for your building
QGEN: Average generator output during peak heating season (typically much
less than rated capacity) in BTUs / Hour
QPIPE: Heat loss from distribution piping during peak heating season. Typically
about BTUH / LF
QO: Heat used by other buildings on the waste heat system (sometimes this is
prioritized by order of connection, so be careful)

22. HEAT RECOVERY RULES OF THUMB:
Generator Output: 1/3 Electricity, 1/3 Jacket heat, 1/3 Stack loss
BTU / KW-Hr (Available Jacket Heat)
100,000 BTU delivered heat = 1 gallon of diesel
Annual Fuel Saved = .3 x Power plant annual fuel used x 0.6
Pumping Energy Costs <= 10% Fuel Value

23. BREAK EVEN TEMPERATURE DIFFERENCE
PPUMP x CE x 100
PPUMP x CE x 100
TBR = +
COIL x UAHX
900 x GPM x COIL
TBR: Break even temperature difference between Generator Heating Supply
and Building Heating Return (Deg F)
PPUMP: Pump power (W)
CE: Electrical cost ($ / kWh)
COIL: Fuel cost ($ / Gallon) (80% efficiency assumed)
UAHX: Heat exchanger U factor multiplied by HX area (BTU/ Hr x Deg F)
GPM: Heat exchanger glycol flow rate (GPM)
(This formula only applies in special case of counterflow HX with matching flow rates and sufficient heating demand to use all of the waste heat)
An example: AVEC charges 30% of offset fuel cost, electricity is $0.20 / KWH (PCE price), Fuel is $7.00 / Gal, Pump power is 850W
TBR =

24. ESTIMATING WASTE HEAT DEMAND
QD =
QBLG + QPROC
QD: Waste heat demand (typically does not include dryers)
QBLG: Building envelope heat losses (must engineer heating system for lower
temperatures than typical heating systems)
QPROC: Heat required by process systems (includes circulation loops, raw water
heat add, storage tanks, etc. This is where waste heat really shines)

25. SELECTING A HEAT RECOVERY STRATEGY
Direct heat add to potable water:
Double wall shell and tube, independent of boiler system (Kiana)
Small system with single boiler:
Pipe heat exchanger in series with boiler (Chenega Bay)
Large system with multiple boilers:
Pipe heat exchanger in primary / secondary arrangement (Kwigillingok)

26. GENERATOR HEAT RECOVERY ARRANGEMENT

27. RECOVERED HEAT INTO POTABLE WATER

28. HEAT EXCHANGER IN SERIES WITH BOILER

29. PRIMARY / SECONDARY HEAT EXCHANGER DIAGRAM

30. Minto Heat Recovery

31. WASTE HEAT CONTROLLER Turns on at 8 Deg F difference
Turns off at 4 Deg F difference
Built in HOA switch.
Provides 1p/2t switch which can handle a 1 HP pump.

32. BTU METER

33. Plate / Frame Heat Exchanger

34. Brazed Plate Heat Exchangers

35. Shell & Tube Heat Exchangers

36. Typical pumps

37. AMOT Valve

38. DESIGN COMMENTS Use Brazed Plate or Plate / Frame heat exchangers
Provide controls to ensure heat is not transferred back to generator cooling system.
Provide controls to minimize electric power consumption
Provide BTU monitoring if being billed by local utility
Provide pressure relief on pipeline
Provide strainers on both sides of heat exchanger (reduces cleaning of heat exchanger).
Provide air separator on pipeline side of system.
Provide glycol system monitoring and makeup.
Provide expansion compensation
Don’t use HDPE pipe. Copper, Steel, PEX, Stainless steel.
Monitor pipeline for leaks and pressure.

40. Questions?